1. Field of the Invention
The present invention concerns the manufacture of optical lenses and especially, but not exclusively, ophthalmic lenses from polymerizable synthetic materials.
2. Description of the Prior
Three operations are involved in the manufacture of an optical lens.
The first step is to assemble the mold which conventionally comprises two molding shells and an annular closure member fitting around the molding shells to define therewith the required molding cavity.
Next, the molding assembly is filled with the molding material, conventionally by pouring the molding material into the molding cavity through an opening provided for this purpose in the closure member at the periphery of the molding shells.
The final operation is to polymerize the molding material and the present invention is more especially, but not exclusively, concerned with the situation in which polymerization is at least begun by exposure.
At present these three operations of assembling the mold, filling the mold and at least starting polymerization of the molding material are conducted at different stations.
First the mold is assembled at an assembly station where the annular closure member to fit around the molding shells is usually separate from the molding shells, being either a seal in which the molding shells are nested or a sleeve which fits around their edge.
Next is a dedicated filling station where, by process that is at least in part automated, the mold to be filled is placed under a filling device which delivers a specific dose of molding material to it via a nozzle.
Finally, polymerization is at least started at another dedicated station at which the mold filled with polymerizable synthetic material is exposed to the necessary source of radiation and/or heat.
Conveyor means are required for transferring the molds between the stations, almost always with intermediate storage.
The process is therefore complex, which increases costs.
A general object of the present invention is to provide a more economical method of manufacturing a polymerizable synthetic material optical lens and a device for implementing this method.